The present invention generally relates to an image forming apparatus wherein cyan (C), magenta (M), and yellow (Y) color image forming units for forming color images are provided on one side of an intermediate transfer medium (such as an intermediate transfer belt), and a black (Bk) toner image forming unit is provided on the other side of the intermediate transfer medium, and particularly relates to an image forming apparatus whose members can be maintained with ease without reducing the strength of an apparatus main body.
Conventionally, a so-called tandem-type image forming apparatus is known as an image forming apparatus for forming color images using cyan (C) toner, magenta (M) toner, yellow (Y) toner and black (Bk) toner. In this type of image forming apparatus, image forming units for respective colors C, M, Y and Bk, each including a photoreceptor drum and a developing section, are arranged in order from the upstream side in a transport direction of a recording sheet, and respective color toner images formed on the photoreceptor drums are superimposed on a recording sheet in order, thereby forming a color image on the recording sheet.
In the described conventional tandem-type image forming apparatus, even when forming monochrome (black-and-white) images, it is required to go through not only Bk image forming processes but also C, M, and Y color image forming processes, and thus it is difficult to perform a high speed printing of a black-and-white image which is expected to be performed most frequently.
In response, for example, Japanese Unexamined Patent Publication No. 341617/1993 (Tokukaihel 5- 341617, published on Dec. 24, 1993) discloses a structure which permits the formation of images at high speed almost as high as the speed of image forming apparatuses for forming only black-and-white images, wherein C, M and Y color recording processing sections adopting an intermediate transfer system are provided separately from a black-and-white recording processing section, and a tandem system is adopted between the color recording processing sections and the black-and-white recording processing section.
The described conventional image forming apparatus is arranged such that a door formed on the front face (the user""s side) of the apparatus main body in an axial direction of a photoreceptor is capable of opening and closing so that various maintenance operations of developing units and image holding member units (such as a refill for toner consumed, etc.) can be performed. Specifically, with the door opened, a developing unit or an image holding member unit is pulled out of the apparatus by sliding it along the axial direction to allow an maintenance operation of the units such as a refill for toner consumed, etc., to be performed.
FIG. 10 shows an example of the image forming apparatuses adopting the above sliding mechanism. In this image forming apparatus, toner image forming stations 101 to 104 for respective colors C, M, Y and Bk are disposed so as to surround an intermediate transfer belt.
The toner image forming stations 101 and 104 respectively include image holding member units 101a and 104a, and developing units 101b and 104b. Further, each of the image holding member units 101a and 104a includes a photoreceptor for forming thereon an electrostatic latent image according to image data. The developing units 101b and 104b are provided for developing electrostatic latent images formed on respective surfaces of the photoreceptors using toner. Similarly, the toner image forming stations 102 and 103 are provided with the image holding member units and the developing units respectively. The respective image holding member units and the developing units of the toner image forming stations 101 to 104 are all slidable in the axial direction of the photoreceptors, and the front face of the apparatus main body is positioned at one end in the axial direction of the photoreceptors. Further, a door 105 is formed on the front face of the apparatus main body so as to be capable of opening and closing.
According to the foregoing structure, with the door 105 opened, by pulling a predetermined unit subjected to the maintenance operation in the axial direction of the photoreceptors, maintenance operations of the predetermined unit can be performed. Further, upon completing the maintenance operation, by pushing back the predetermined unit to its installation position in the apparatus main body, and closing the door 105, a normal copying operation can be performed.
However, according to the structure shown in FIG. 10, all the toner image forming stations 101 to 104 slide along the axial direction, and thus the size of the door 105 formed in the axial direction is needed to be large. It is therefore required to form a large opening 106 for the door 105 in the support frame on the front face of the apparatus main body, which results in a reduction in strength of the main body apparatus. This problem becomes serious especially when using the apparatus with the main body apparatus tilted for a long time, as a damage on an element (mirror, LSU, etc.) which requires high precision may occurs due to the reduction in strength, thereby leading to a problem of a displacement of respective color toner images.
It is an object of the present invention to provide an image forming apparatus in which various maintenance operations of each unit can be performed while maintaining a sufficient strength of an apparatus main body, whereby degradation of image quality with life can be avoided for a long period of time.
In order to achieve the above object, an image forming apparatus of the present invention is characterized by including:
a plurality of image forming stations for respectively forming images in different colors,
wherein at least one of the plurality of image forming stations and rest of the plurality of image forming apparatuses are slidable in mutually different directions respectively through openings formed on an apparatus main body in respective sliding directions.
According to the above arrangement, the image forming stations corresponding to respective colors do not slide all in the same direction, but in two different directions. Here, the number of image forming stations which slide in each direction is not limited, and one or a plurality of image forming stations may slide in each direction. In any case, the image forming stations slide in mutually different directions through respective openings formed on the apparatus main body in respective sliding directions.
For example, in the case where one of the openings is formed in the axial direction of image holding members provided in the image forming stations, respective image forming stations being aligned in parallel in a direction orthogonal to the axial direction. In the conventional arrangement, all the image forming stations slide in the axial direction, and thus the opening formed in the axial direction is required to have a large size, and thus the reduction in strength of the apparatus main body having the opening cannot be avoided.
However, according to the arrangement of the present invention, by dividing the sliding direction of the image forming stations into two, for example, the number of image forming stations which slide in the axial direction of the image holding members provided in the image forming stations can be simply reduced. As a result, a size of the opening formed in the axial direction can be made smaller, and thus a reduction in strength of the apparatus main body can be suppressed. Therefore, even in the case where the apparatus is used for a long time with an apparatus main body tilted due to installation condition, the resulting displacement of each image forming station inside the apparatus can be prevented without causing a distortion in the apparatus main body. As a result, a displacement of images formed by the image forming stations for respective colors can be suppressed, and thus a degradation of image quality can be avoided. Moreover, since each of the image forming stations is slidably mounted, maintenance operations of respective image forming stations can be surely performed.
In order to achieve the above object, another image forming apparatus is characterized by including:
a first image forming section for forming an image;
a second image forming section for forming an image in different color from the image formed by the first image forming section; and
an intermediate transfer medium disposed between the first image forming section and the second image forming section,
wherein the image formed by the first image forming section and the image formed by the second image forming section are transferred onto a recording medium by the intermediate transfer medium, and
the first image forming section and the second image forming section are slidable in mutually different directions respectively through openings formed on an apparatus main body in respective sliding directions.
In the above structure, first image forming section may be a group of image forming stations for respectively forming color images in different colors. On the other hand, the second image forming section may be an image forming station for forming images in different color from that of the above color images, such as a black-and-white image.
According to the above structure of having the intermediate transfer medium between the first image forming section and the second image forming section, for example, a black-and-white image formed by the second image forming section can be transferred onto a recording medium in a circulation of the intermediate transfer medium from the second image forming section to the first image forming section. Namely, the black-and-white image can be transferred onto the recording medium without passing through a transfer region for color image on the intermediate transfer medium. As a result, a high speed copying of a black-and-white image can be performed.
According to the above structure, the first image forming section and the second image forming section do not slide in the same direction, but in mutually different directions through respective openings formed on the apparatus main body in respective sliding directions. In this case, the size of the opening formed in each sliding direction can be set according to the size of the first image forming section or the second image forming section. Therefore, compared with the case wherein both the first image forming section and the second image forming section slide in the axial direction of the image holding members provided in respective image forming stations, the size of each opening can be made significantly smaller.
Therefore, according to the above arrangement, by making each opening smaller, the reduction in strength of the apparatus main body can be suppressed. Therefore, even in the case where the apparatus is used for a long time with the apparatus main body tilted due to installation condition, the resulting displacement of each image forming station inside the apparatus can be prevented without causing a distortion in the apparatus main body. As a result, a displacement of an image formed by an image forming station in each color can be suppressed, and thus degradation of image quality with life can be avoided. Moreover, since each of the image forming stations is slidably mounted, maintenance operations of each image forming station can be surely performed.
The above image forming apparatus may be further arranged such that:
the first image forming section and the second image forming section include, for respective different colors, image holding members for holding electrostatic latent images according to the image data, the image holding members being rotatable about respective axes aligned in a same direction, and
one of the first image forming section and the second image forming section is slidable in an axial direction of the image holding members, and other of the first image forming section and the second image forming section is slidable in a direction orthogonal to the axial direction.
According to the above structure, the first image forming section and the second image forming section slide in mutually orthogonal directions, and one of the sliding directions is the axial direction of the image holding members. Moreover, the first image forming section and the second image forming section are arranged such that the respective axial directions of the image holding members are aligned. Therefore, compared with the case of sliding both the first image forming section and the second image forming section in the axial direction of the image holding members, the number of image forming stations which slide in the axial direction can be reduced, and an area of the face of the image forming station vertical to the axes can be made smaller. As a result, the size of the opening formed in the axial direction corresponding to the vertical face can be surely reduced, and whereby a reduction in strength of the apparatus main body can be surely reduced.
In the above arrangement, one of the first image forming section and the second image forming section is provided for forming black-and-white images, and other of the first image forming section and the second image forming section is provided for forming color images.
According to the above arrangement, the image forming stations for forming color images and the image forming station for forming black-and-white images can be separately provided with the intermediate transfer medium in between. As a result, for example, in a circulation of the intermediate transfer medium, only a black-and-white image can be transferred onto a recording medium via the intermediate transfer medium, which permits a high speed copying of the black-and-white image.
The above image forming apparatus may be further arranged such that the first image forming section is slidable in an axial direction of the image holding members, and the second image forming section is slidable in a direction orthogonal to the axial direction.
According to the above arrangement, the opening in the axial direction of the image holding member can be set in consideration of only the size of the first image forming section for forming color images. Therefore, compared with the arrangement of sliding both the first image forming section and the second image forming section in the axial direction, the size of the opening in the axial direction can be made significantly smaller, thereby surely suppressing a reduction in strength of the apparatus main body.
Alternately, it may be arranged such that the first image forming section is slidable in a direction orthogonal to an axial direction of the image holding members, and the second image forming section is slidable the axial direction.
According to the above arrangement, the opening in the axial direction of the image holding member can be set in consideration of only the size of the second image forming section for forming black-and-white images. Therefore, compared with the arrangement of sliding both the first image forming section and the second image forming section in the axial direction, the size of the opening in the axial direction can be made significantly smaller, thereby surely suppressing a reduction in strength of the apparatus main body.
The forgoing image forming apparatus may further includes guide means for guiding sliding movements of the first image forming section or the second image forming section in such a manner that the first image forming section or the second image forming section is separated from or is in contact with the intermediate transfer medium interlocking with the sliding movements of the first image forming section or the second image forming section, respectively.
According to the above structure, for example, when sliding the first image forming section to be pulled out of the apparatus main body, the sliding movements of the first image forming apparatus are guided by the guide means so as to slide after being separated from the intermediate transfer medium. On the other hand, when sliding the first image forming apparatus to be mounted in its installation position of the apparatus main body, the sliding movements of the first image forming section are guided by the guide means so as to come in contact with the intermediate transfer medium upon completing its sliding movements. The above structure of guiding the sliding movements of the first image forming section can be applied to the second image forming section.
According to the foregoing arrangement, the first or second image forming section is not always in contact with the intermediate transfer medium in its sliding movements. As a result, a friction between the first or second image forming section and the intermediate transfer medium can be surely prevented, and thus a damage on the first image forming section, the second image forming section, and the intermediate transfer medium can be surely prevented.
Moreover, as the first image forming section or the second image forming section is separated from and is brought in contact with the intermediate transfer medium interlocking with its sliding movements by the guide means, a separately provided mechanism for preventing such problem (a lever for manually switching contact and non-contact between the first or second image forming section and the intermediate transfer medium) can be omitted.
Therefore, according to the forgoing arrangement, the structure for preventing a friction between the first or second image forming section and the intermediate transfer medium can be achieved without increasing the number of the components. Moreover, sliding movements of the first and second image forming sections, and the switching between contact/non-contact between the first image forming section and the intermediate transfer medium can be performed simultaneously by the simple structure of adding the guide means.
The forgoing image forming apparatus may be arranged such that the first image forming section and the second image forming section include for respective different colors pairs of i) image holding member units for forming electrostatic latent images according to image data and ii) developing units for developing the electrostatic latent images.
According to the above arrangement, maintenance operations of the image holding member units and the developing units for respective colors can be performed simultaneously by the sliding movements of the first and second image forming sections.
The forgoing image forming apparatus may be arranged such that each of the image holding member units includes a developing section for developing an electrostatic latent image formed on an image holding member with toner in corresponding color, and a developer vessel for supplying the toner to the developing section.
According to the above arrangement, various maintenance operations of the developing section and the developing vessel which constitute each developing unit can be performed simultaneously by sliding the first and second image forming sections.
The forgoing image forming apparatus may be arranged such that each of the image holding member units includes an image holding member for holding the electrostatic latent image, a charger for charging a surface of the image holding member, and a cleaning unit for cleaning the surface of the image holding member.
According to the foregoing arrangement, various maintenance operations of the image holding member, the charger and the cleaning unit which constitute each image holding member unit can be performed simultaneously by sliding the first and second image forming sections.
For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings.